Calendering device



Oct. 30, 1934. J. A. MQcRoHAN CALENDERING DEVICE INVENTOR Filed April 16. 1932 JoH/v A. MfcRQfMN ATTORNEY Patented Oct. 30, 1934 UNITED STATES PATENT OFFICE CALENDERING DEVICE Application April 16, 1932, Serial No. 605,656

5 Claims.

In the calendering of plastic stocks, particularly rubber stocks, in which high powered accelerators of Vulcanization have been incorporated, it frequently happens that the stock accumulates at some point in the bite of the calender rolls and becomes overheated, causing premature vulcanization which is technically known as scorching or burning, thereby rendering it useless and spoiling the calendered stock. For equalizing the thickness of the stock and eliminating imperfections, devices have been suggested which press the stock between the calender rolls and distribute the same thereovei'. Such a device is described and claimed in the patent to Kearns 1,277,279 dated Sept. 3, 1918. While devices of this character may be satisfactorily utilized under certain conditions in enabling the stock to be evenly spread throughout the length of calender rolls and thus prevent it from accumulating at certain points, such devices do not prevent the premature vulcanization or burning of rubber stock in which high powered accelerators of vulcanization have been incorporated. Due to the fact that it has heretofore been impossible, without so burning the stock, to utilize known devices for preventing the accumulation of rubber stock adjacent the bite of the calender rolls, it has been impossible to calender stock into sheets substantially greater in thickness than .025 of an inch. The reason for this limitation is because it was necessary to carry large banks of stock adjacent the bite of the calender rolls in order to calender sheets of greater thickness and these large banks were susceptible to being overheated and burned by virtue of the constant friction created by contact with the calender rolls or with the spreading or equalizing devices designed to cooperate therewith.

The present invention relates to the art of calendering plastic stock and overcomes the difiiculties heretofore experienced in the burning of rubber stocks on the calender. By virtue of this invention rubber stocks are not only uniformly distributed on the calender rolls and thus prevented rom accumulating at certain points adjacent the bite thereof, but they are also prevented from overheating and burning. Moreover by the use of the present invention it is possible to run stocks into sheets considerably over .025 of an inch, in fact it is possible to run stocks up to a gauge far in excess of any thickness heretofore run without doubling, that is without laminating relatively thin stocks into a sheet of the desired thickness.

While the invention is capable of being utilized in various forms, it will here be described as it is embodied in the example illustrated in the accompanying drawing in which:

Fig. l is a side elevation of a calendering apparatus embodying the invention, the elevation being taken at a slight angle in the direction of the arrow A of Fig. 3.

Fig 2 is a plan view taken in the direction of the arrow B of Fig. 3, of the adjusting device with the associated parts partly broken away;

Fig. 3 is a section taken along the line 3 3 of Fig. 1.

To the frame 1 of the machine, at each side of the calender rolls 17 and 18, is fixed a support 2 70 which may be spaced from the frame by means of legs 3. Integral with support 2 is provided a bracket 4 whose upper end is provided with a tapped hole provided with screw threads adapted to carry screw 5. The upper end of this screw is provided with a hand wheel 6 and the lower end with a circular flange 7 tting into slot 8 in movable carriage 9. This carriage is adapted to slide on guides l0 provided in support 2 and is provided with guideways 1l disposed about the 80 guides 10.

To carriage 9 is fixed a spreader bar 12, illustrated in the example of the drawing as a rectangular bar whose bottom edge is rounded at 13 into cylindrical form. Lengthwise through the 85 bottom of the bar is drilled a conduit 14 arranged to communicate with the top of the bar through orifices 15 (that at one end only being shown). Nipples 16 are arranged to communicate with each orice 15. One nipple is arranged to communicate, as by flexible piping, with a source of cold water supply and the other is arranged to communicate with a point of drainage.

The operation of the device is as follows: Having arranged the spreader bar device in brackets 4, by inserting the anges 7 into slots 8 in the carriage 9 at each end of the device, hand wheels 6 are turned to bring carriages 9 into the position required to adjust bar 12 adjacent the bite of the calender rolls 17 and 18. By the arrangement 100 illustrated the clearance between bar 12 and roll 18 may be adjusted as desired. When the proper clearance is obtained, the calender rolls are started to rotate and stock charged into the machine. The bank which forms about the bite of the calender rolls is distributed uniformly throughout their length by the operating edge of bar l2. Water is run through conduit 14 in order to prevent bar 12 and the stock contacting therewith, 1w

from overheating. Adjustment may be made in the temperature and rate of ow of the cooling water so that the proper temperature of the stock may be maintained.

The operating edge 13 of the bar 12 is preferably made slightly convex throughout its length. The amount of convexity may be varied dependent primarily on the width of the rolls and the thickness of the stock desired, although it has been found in practice that T15 of an inch crown per foot of bar is best suited for general use. The crown is desirable in forcing the stock away from the center of the rolls Where it ordinarily tends to accumulate. The shape of the bar may, however, be other than crowned as it has been found that a substantially straight bar is satisfactory for some uses as is also one which is slightly concave throughout the direction of its length. The latter is sometimes adapted for calendering relatively thin stocks.

By virtue of this invention the stock is not only distributed uniformly over the calender rolls but it is also prevented from becoming overheated and burned. Moreover it is thus possible to use large banks of stock and calender them into sheets of appreciable thicknesses, without danger of the stock being prematurely vulcanized or burned by lvirtue of the heat generated by the friction between the relatively movable operating members. It is apparent that the stock may be run for any length of time without liability of spoiling.

Without intent to limit the invention otherwise than as required by the prior art, the same will be best understood by reference to the following claims.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. In a rubber calender, a pair of calendering rolls for forming a sheet from a bank of rubber stock disposed adjacent their bite, and stationary stock cooling and distributing means disposed between the rolls and outside the bite in position to be embedded in the bank of uncalendered stock lying against said rolls, whereby overheating and burning of the bank of stock between the rolls is prevented.

2. A process for treating plastic stock which comprises maintaining a bank of the plastic stock adjacent the bite of a pair of calender rolls, and internally cooling and distributing the bank.

3. A process for treating plastic rubber stock which comprises maintaining a bank of such stock adjacent the bite of a pair of calender rolls and simultaneously cooling and distributing said bank.

4. A process for calendering plastic stock, which comprises maintaining a relatively large bank of stock adjacent the bite of a pair of calender rolls and in contact with each of them, and sheeting out the stock while internally cooling the bank and spreading it to prevent localized enlargement thereof.

5. In a rubber calender, a pair of calender rolls for sheeting rubber from a bank disposed adjacent their bite, a stationary stock distributing bar disposed adjacent the bite of said rolls in position to be embedded in the bank of uncalendered stock, the inner edge of said bar being slightly convexed, and means for cooling said bar.

JOHN A. MCCROHAN.

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